The present invention relates to a connector by which helically grooved electrical conduit can be rigidly secured in a housing such as a junction box, fixture or the like.
The problem of securely fastening flexible electrical conduit in a junction box has been solved in several ways in the past. One such solution involves die cast sleeves which are threaded into the junction box and then secured by a locking nut. Conduit is then fed through the sleeves and clamped by screw-tightening a bar assembly to bear upon the inserted conduit. While this method serves the ultimate purpose of holding the electrical conduit in the junction box, it has several drawbacks.
Connectors involving die cast sleeve assemblies typically have several separate subparts which are manufactured and then loosely assembled and sold as a connector unit. Individual assembled units must then be disassembled for installation at the worksite. Such a complicated manufacturing and installation technique is very expensive and time-consuming. Also, junction boxes of the type in which the connector of the present invention are designed for use are often located in out-of-the-way places to which access is limited. Die cast sleeve assemblies have proven difficult to use where needed because the numerous small parts require ample space and a dexterous hand to assemble and position in the junction box. Finally, die cast assemblies by their very nature tend to be somewhat weighty and costly.
Various lightweight and relatively inexpensive devices have been proposed as connectors to supplant die cast sleeve assemblies and thus solve the problem at hand. These are referred to as clips and two such clip designs are found in U.S. Pat. Nos. 3,858,151 and 4,012,578 respectively. These patents disclose clips having body portions of various cross-sections to enclose and improve the holding action on conduit to provide good electrical conductivity between the conduit and the junction box. Clip devices of the kind patented, however, have been less than satisfactory because they do not hold the flexible electrical conduit in place as securely as required. In U.S. Pat. No. 3,858,151, for example, a clip is described which has a "tubular body portion" only a pair of barbs which engage the helical groove of the electrical conduit. These barbs, however, are so few and located so closely together that they engage the conduit along only a relatively short portion of its axial length. As a result, the conduit tends to pull loose from the junction box by becoming unscrewed.
In U.S. Pat. No. 4,012,578, a connector clip is described which has a "body portion generally defined by flat walls". The body portion rather than being cylindrical as in the patent discussed above has a triangular, square, pentagonal or hexagonal cross-section, the flat walls assertedly better engaging the conduit outer surface. In practice, however, the patented device fails to engage the conduit evenly and the conductor is only loosely connected to the junction box, remaining subject to unwanted disengagement.
Accordingly, an object of the present invention is an improved mechanical and electrical connection of a conduit to a junction box or the like.
It is another object of the present invention to provide an easily manufactured connector of a one-piece construction.
It is still another object of the present invention to provide a connector which requires no prior assembly and which can be easily and inexpensively installed.
A further object of the invention is to reduce the cost and complexity of connectors by stamping them from relatively light metal.